Hitherto, the multi protocol label switching (MPLS) system has been available as a method of transferring packet data. The MPLS system is the technology of communications with high speed by assigning an identifier, which is referred to as a label, to packet data.
Additionally, the multi protocol label switching—transport profile (MPLS-TP) system of the MPLS system has been available in recent years, where the MPLS system provides an improved operation administration and maintenance (OAM) functions.
The unidirectional path switched ring (UPSR) system, which is used in a network of the synchronous digital hierarchy (SDH) transfer system, has been available as the system having OAM functions in a communication network. In the UPSR system, a network includes a plurality of node apparatuses arranged to form a ring, and a node apparatus functioning as a data source transmits the same data in two directions of the ring, that is, through an active line and a standby line under normal conditions. Further, in the UPSR system, a node apparatus functioning as the data destination receives the data from the active line under normal conditions. When a failure occurs in the active line, the destination node apparatus changes the active line to the standby line to receive the data.
However, increasing of the utilization efficiency of the lines in an MPLS network has not been considered in the related technologies.
To increase the efficiency of the MPLS network, the source node apparatus may transmit the same data to paths extending in both directions, that is, the active and the standby lines, and the destination node apparatus may change the active line to a different line if needed, as is the case with the UPSR system.